Bernie Masters is a geologist/zoologist who spent 8 years as a member of the Western Australian Parliament. Married to Carolina since 1976 and living in south west WA, Bernie is involved in many community groups. This blog offers insights into politics, the environment and other issues that annoy or interest him. For something completely different, visit www.fiatechnology.com.au for information about vegetated floating islands - the natural way to improve water quality.

Tuesday, March 06, 2018

Plastics - some truths you need to know

The known unknowns of plastic pollution

So far, it seems less bad than other kinds of pollution (about which less fuss is made)

March 3rd 2018 - The Economist

MR
MCGUIRE had just one word for young Benjamin, in “The Graduate”:
plastics. It was 1967, and chemical engineers had spent the previous
decade devising cheap ways to splice different hydrocarbon molecules
from petroleum into strands that could be moulded into anything from
drinks bottles to Barbie dolls. Since then global plastic production has
risen from around 2m tonnes a year to 380m tonnes, nearly three times
faster than world GDP.

Unfortunately, of the 6.3bn tonnes of
plastic waste produced since the 1950s only 9% has been recycled and
another 12% incinerated. The rest has been dumped in landfills or the
natural environment. Often, as with disposable coffee cups, drinks
bottles, sweet wrappers and other packets that account for much of the
plastic produced in Europe and America, this happens after a brief,
one-off indulgence. If the stuff ends up in the sea, it can wash up on a
distant beach or choke a seal. Exposed to salt water and ultraviolet
light, it can fragment into “microplastics” small enoughto find their
way into fish bellies. From there, it seems only a short journey to
dinner plates.

Countries
as varied as Bangladesh, France and Rwanda have duly banned plastic
bags. Since last year anyone offering them in Kenya risks four years in
prison or a fine of up to $40,000. In January China barred imports of
plastic waste, while the European Union launched a “plastics strategy”,
aiming, among other things, to make all plastic packaging recyclable by
2030 and raise the proportion that is recycled from 30% to 55% over the
next seven years. A British levy on plastic shopping bags, introduced in
2015, helped cut use of them by 85%. On February 22nd Britain’s
environment secretary, Michael Gove, mused about prohibiting plastic
straws altogether.

Fearful for their reputations, big companies
are shaping up. Coca-Cola has promised to collect and recycle the
equivalent of all the drinks containers it shifts each year, including
110bn plastic bottles. Consumer-goods giants such as Unilever and
Procter & Gamble vow to use more recycled plastics. McDonald’s plans
to make all its packaging from recycled or renewable sources by 2025,
up from half today, and wants every one of its restaurants to recycle
straws, wrappers, cups and the like.
The perception of plastics as
ugly, unnatural, inauthentic and disposable is not new. Even in “The
Graduate” they symbolised America’s consumerism and moral emptiness.
Visible plastic pollution is an old complaint, too (years ago, plastic
bags caught in trees were nicknamed “witches’ knickers”). What is new is
the suspicion that microplastics are causing widespread harm to humans
and the environment in an invisible, insidious manner. “Blue Planet 2”, a
nature series presented by Sir David Attenborough that aired in Britain
last October and in America in January, made the case beautifully. But
the truth is that little is known about the environmental consequences
of plastic—and what is known doesn’t look hugely alarming.

A load of rubbish

We can be surest about how much plastic is produced and where it ends up. In a paper published last year in Science Advances,
Roland Geyer of the University of California, Santa Barbara, and his
colleagues put the cumulative amount of solid plastic waste produced
since the 1950s that has not been burned or recycled at 4.9bn tonnes
(see chart 1). It could all have been dumped in a landfill 70 metres
deep and 57 square kilometres in area—that is to say, the size of
Manhattan.

If only it had all remained on land, or even washed up
on beaches, where it could be collected. A bigger environmental worry is
that much plastic has ended up in the ocean, where, dispersed by
currents, the stuff becomes virtually irretrievable, especially once it
has fragmented into microplastics. Computer models suggest that seas
hold as many as 51trn microplastic particles. Some are the product of
larger pieces breaking apart; others, like microbeads added to
toothpaste or face scrubs, were designed to be tiny.

Whereas salt
and sunlight can cause plastics physically to break apart into smaller
pieces, chemically the hydrocarbons linked together into the polymer
chains of which plastics are made do not spontaneously decompose into
other compounds. Like crude oil, from which most polymers are derived,
that happens only if they are burned at a high temperature to release
mainly carbon dioxide and water. In normal conditions plastic simply
accumulates in the environment, much as carbon dioxide does in the
atmosphere.

Even if the flow of plastic into the sea, totalling
perhaps 10m tonnes a year, was instantly stanched, huge quantities would
remain. And the flow will not stop. Most of the plastic in the ocean
comes not from tidy Europe and America, but from countries in
fast-developing East Asia, where waste-collection systems are flawed or
non-existent (see map). Last October scientists at the Helmholtz Centre
for Environmental Research, in Germany, found that ten rivers—two in
Africa and the rest in Asia—discharge 90% of all plastic marine debris.
The Yangtze alone carries 1.5m tonnes a year.

On
current trends, by 2050 there could be more plastic in the world’s
waters than fish, measured by weight. Such numbers frighten people and
change their behaviour. Nine in ten Europeans worry about plastic’s
impact on the environment. More than half told pollsters for
Eurobarometer in 2017 that they try to forgo plastic bags when shopping.
By comparison, only one-tenth consider fuel-efficiency when buying a
new car. Unlike other kinds of pollution, plastic is an eyesore, notes
Liz Goodwin of the World Resources Institute, a think-tank. Yet if a
comprehensive league-table of environmental ills existed—which it does
not—plastics would not top it.

Just 10% of 3.6m tonnes of solid
waste discarded each day the world over is plastic. Whereas filthy air
kills 7m people a year, nearly all of them in low- and middle-income
countries, plastic pollution is not directly blamed for any. A report
last year by the Lancet Commission on pollution and health, which put
the total number of pollution-related deaths at 9m, mentions plastics
once in its 45 pages.
On land, the damage from litter, which
exercises many anti-plastic campaigners, is limited. Most refuse does
not spread too far beyond population centres, where (at least in
principle) it can be managed. At sea, most plastics end up in vast
rubbish patches fed by ocean circulation patterns, the biggest of which
can be found in the north Pacific.

Mid-ocean gyres are fortunately
neither especially rich in fauna nor particularly biodiverse. The
effects of plastics on busier bits of the ocean, such as reefs, have
been little studied. One paper, published this year in Science
by Joleah Lamb of Cornell University and colleagues, linked plastic
litter to coral disease near Indonesia and Myanmar. But little similar
work exists for other sedentary species, let alone slippery migratory
ones.

Researchers have identified 400 species of animal whose
members either ingested plastics or got entangled in it. It is known
that because polymers repel water (which is why droplets form on their
surface), plastic particles also attract certain compounds from their
surroundings. Some of these could be toxic. Laboratory studies have
shown that if swallowed by fish, compounds in plastic fragments can be
absorbed from the digestive tract into flesh. However, no studies have
so far been performed to test whether such toxins concentrate up the
food chain, as mercury does in fish. The only direct evidence of plastic
entering the human diet is a study by Belgian scientists who discovered
plastic fragments in mussels. Unlike fish, bivalves are eaten whole,
guts and all.

Munching moules-frites
seasoned with a pinch of plastic may sound unappetising but it is hard
to say if it is dangerous, says Stephanie Wright, who studies the
subject at King’s College, London. Polymers are chemically inert, and so
do not themselves present a health risk. Some common additives such as
phthalates (which soften PVC) or bisphenol-A (which hardens many types
of plastic used in consumer goods) are chemically akin to human
hormones, and might therefore disrupt them in high concentrations. For
decades both have been licensed for use in everything from pipes to
shampoo bottles because human exposure was unlikely to exceed safe
limits. America now bans some phthalates in toys and child-care products
because of potential harm to growing children.

Weighing the damage

Trucost,
a research arm of Standard & Poor’s, a financial-information
provider, has estimated that marine litter costs $13bn a year, mainly
through its adverse effect on fisheries, tourism and biodiversity. It
puts the overall social and environmental cost of plastic pollution at
$139bn a year. Of that half arises from the climate effects of
greenhouse-gas emissions linked to producing and transporting plastic.
Another third comes from the impact of associated air, water and land
pollution on health, crops and the environment, plus the cost of waste
disposal.

To put that into perspective, the United Nations
Development Programme says that the costs of overfishing and fertiliser
run-off amount to some $50bn and $200bn-800bn a year, respectively. By
2100 ocean acidification, which is caused by atmospheric carbon dioxide
dissolving into water, could cost $1.2trn a year. The costs of rapid
ocean warming caused by human-induced climate change are hard to fathom
but are likely to be enormous.

The overall cost of plastic
pollution compares favourably with other sorts of man-made harm mostly
because plastics are light. Making a kilogram of virgin plastic releases
2-3kg of carbon dioxide, about as much as the same amount of steel and
five times more than wood. But a product made of plastic can weigh a
fraction of a comparable one made of other materials.

That is why
replacing plastic with other things could raise environmental costs at
least fourfold, according to Trucost’s analysts. This is even true of
the various virtue-signalling alternatives to plastic bags. A British
government analysis from 2011 calculated that a cotton tote bag must be
used 131 times before greenhouse-gas emissions from making and
transporting it improve on disposable plastic bags. The figure rises to
173 times if 40% of the plastic bags are reused as bin liners,
reflecting the proportion in Britain that are so repurposed. The carbon
footprint of a paper bag that is not recycled is four times that of a
plastic bag.

And
other materials could not replace plastics in all circumstances.
Imagine a hospital without surgical gloves, or promiscuity without
condoms. By keeping food fresh for longer, plastic packaging
substantially reduces organic waste, itself a growing environmental
concern. In 2015 J. Sainsbury, a British grocer, reduced waste in a
beefsteak line by more than half by using plastic vacuum packaging.

Plastic
pollution “is not the Earth’s most pressing problem”, in the words of
one European official. But, he immediately adds, just because plastics
may not be the biggest problem facing humanity does not make them
trouble-free. As scientists never tire of repeating, more research is
needed. It is the absence of evidence about how plastics influence
health rather than evidence of absence that explains their bit part in
the Lancet Commission report, says Philip Landrigan of the Icahn School
of Medicine in New York, who chaired it.

Fresh science may be
forthcoming. In the past two years Ms Wright has noticed an uptick in
grants for plastics-related research. Erik van Sebille, of Utrecht
University in the Netherlands, recalls that a few years ago a seminar on
ocean plastic pollution organised by America’s National Oceanic and
Atmospheric Administration drew perhaps 200 participants. This year
organisers had to cap attendance at 600 and turn people away.

While
researchers get a better handle on the science, campaigners badger
politicians and browbeat consumers to kick the polymer habit. They often
invoke the precautionary principle. If the impact of something is
uncertain but could be great, the argument goes, better forestall it
just in case. As the proliferation of plastic bans and strategies
suggest, they are having some success.

PET peeves

Much
of this activity makes scarcely a dent in the world’s plastic pollution
problem, however. Some has unintended consequences. Making plastics
biodegradable, by adding corn starch or vegetable oil to
petroleum-derived hydrocarbons, renders them harder to recycle.
Recyclers already struggle to invest in capacity or innovation even in
countries that collect lots of their rubbish. Periodic declines in the
oil price, which makes virgin plastic cheaper, can bankrupt recyclers,
many of which are small or medium-sized companies, says Peter Borkey of
the OECD, a rich-country think-tank.

Meanwhile consumer-goods
firms sometimes say that too little recycled plastic is available to
buy. With costs of some recycled plastic competitive with virgin stuff,
“supply is a bigger issue than cost,” says Virginie Helias, Procter
& Gamble’s vice-president for sustainability. In other words,
erratic demand appears to dampen supply while insufficient supply
inhibits demand. Recyclers everywhere face that problem. There is no
guarantee that targets like the EU’s will solve it.

China’s import
ban may provide the necessary jolt. Introduced as part of a broader
clampdown on pollution, it took waste exporters by surprise. In 2017
European countries shipped a sixth of their plastic waste for disposal
abroad. Most sailed to China. In the short run some surplus waste can go
to Malaysia or India, but those countries’ capacity is a fraction of
China’s. Eventually, refuse exporters will have to deal with more of it
at home.

Building recycling capacity is one option. Incineration
is falling out of favour for heating or electricity generation as
coal-fired plants are replaced with gas, which emits less greenhouse
gases than waste-to-energy plants. From an ecological standpoint,
landfilling is not as bad as it looks, so long as additives that might
leach out of the polymers are prevented from escaping. Plasma recycling,
where refuse is heated to as much as 5,000°C, turning it into
unadulterated hydrocarbons plus a solid residue, looks promising but
remains some way from commercialisation.

To
be disposed of, though, plastic waste must be collected. In Europe,
America and other developed places, virtually all of it is. To eliminate
marine litter in particular, more rubbish needs to be picked in the
leaky Asian countries.

China’s anti-pollution drive may bring
about improvements, although the country now pays more attention to
filthy air and water, which are more pressing concerns. Indonesia has
launched its own National Action Plan on marine plastic. The other big
polluters are eyeing similar measures. What happens there over the next
few decades will matter more than any number of Western plastic-bag
bans.